Keywords: composite connection, openings, non-linear, three-dimensional finite element, moment rotation.

In a composite frame system, the beams support the floor slabs and at each intersection between the beams and column, the columns are usually continuous and the beams are attached to their external faces by connections. It is assumed that these are designed to act as pin joints, but they may be semi-rigid or rigid. Composite slabs and semi-rigid connections constitute a new type of semi-rigid connection. The composite action of the connection is achieved through longitudinal reinforcement, headed shear studs, the concrete itself, the steel beams, steel columns and the fittings (end plate, cleats, etc.). The effect of openings in flange on the behaviour of composite beams with metal-ribbed decking has been investigated [1,2].

This paper described an investigation on the effect of openings in the flange of composite beams to assess the composite connection performance. The current study is based on nonlinear three-dimensional finite element models. A composite joint with flush end-plate connection has been used for this study. Parametric studies of openings location and size have been performed to investigate the effect to the moment rotation and structural behavior of the composite connection.

A three-dimensional non-linear, finite element model was developed using ANSYS [3], to investigate the influence of these openings. The finite element method proved capable of accurately predicting the elastic as well as inelastic moment-rotation of the composite connections. It was found that there was a significant effect on the moment capacity of the connections when the openings were located near the column face area, compared to when they were located far from the column face. It also showed that the opening size in the transverse-axis direction significantly affected the moment capacity of the composite connection, compared to when the opening size was in the longitudinal axis direction.

Based on these results it is suggested that any openings should be located at a distance of L/4 from the end of the beam. It is also suggested the openings need to be cut in a longitudinal axis direction rather than a transverse axis direction. If the openings need to be located over the support position or over beam to column composite connections, then composite beams and composite connections need to be designed carefully, since they significantly affect the moment capacity. It can be concluded that openings in composite beams with deformed decking slabs should be dealt with carefully in relation to their location, size and cutting direction.

1

S. Baharom, R.Y. Xiao, "Finite element modelling of composite beam with opening in ribbed decking slab", Proceeding of 6th International Conference on Steel and Aluminium Structures, 465-472, 2007.

2

R.Y. Xiao, S. Baharom, "Numerical Modelling of the Effect of Opening Location in Composite Beam Flanges with Deformed Decking Floors", in B.H.V. Topping, (Editor), "Proceedings of the Eleventh International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 30, 2007. doi:10.4203/ccp.86.30

3

Swanson Analysis System, "ANSYS Online manual, version 8.0 and Theory Reference", 8th ed., Swanson Analysis System.

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